Re: Workflow management with GNU Guix

[Roel Janssen <roel@gnu.org>]

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Ludovic Courtès writes:

> Hello Guix!
>
> Roel Janssen <roel@gnu.org> skribis:
>
>> So, I would like to propose a new Guix subcommand and an extension to
>> the package management language to add workflow management features.
>>
>> Would this be a feature you are interested in adding to GNU Guix?
>
> I don’t know if it should be in Guix itself (and it’s probably too early
> to think about it), but there’s definitely interest in it!
>
> Pjotr mentioned it before, and Ricardo started a thread on this topic on
> help-guix in February¹, where we discussed something similar to what you
> proposed.  I agree with you that Guix should be a nice tool for the job.
>
> ¹ https://lists.gnu.org/archive/html/help-guix/2016-02/msg00019.html
>
>> I'm currently working on a proof-of-concept implementation that has three
>> record types/levels of abstraction:
>> <workflow>:  Describes which <process>es should be run, and concerns itself with
>>              the order of execution.
>>
>> <process>:   Describes what packages are needed to run the programs involved,
>>              and its relationship to other processes.  Processes take input and
>>              generate output much like the package construction process.
>>
>> <script>:    Short and simple imperative instructions to perform a task. They are
>>              part of a <process>.  Currently, my implementation generates a shell
>>              script that can be either Guile, Sh, Perl or Python.
>
> In the previous discussion, I thought that a gexp would be enough to
> write a derivation that implements a workflow.  That is, basically you’d
> write:
>
>   (define (my-workflow input)
>     (gexp->derivation "result" #~(process-the-thing #$input #$output)))
>
> Maybe it’s all it takes to represent a workflow?  Or maybe my idea of
> what workflows look like is too naive.
>
>> The subcommand I envision is:
>>   guix workflow
>>
>> With primarily:
>>   guix workflow --run=<name-of-workflow-definition>
>>
>> If you are interested in adding any form of workflow management to GNU Guix, I
>> can elaborate on my proof-of-concept implementation, so we can work from there.
>> (or throw everything out of the window and start from scratch ;-))
>
> I’m interested in seeing what it’s like, and examples of it!

I realize I never shared my proof-of-concept implementation.  I attached
my motivations for having a workflow language in Guix, and my code.

The subcommand "guix workflow" does not work (yet) here.  I currently
execute a workflow directly from the REPL.

A final point to note is that I would like to do a second attempt at
designing the workflow language, changing the way we can execute
programs.

Kind regards,
Roel Janssen